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Analysis on FDA warning letters with calibration and maintenance issues

Researched by: CompuCal Calibration Solutions

CompuCal analysed the FDA warning letters data of the last five years with the focus on calibration and maintenance issues. According to the results, 4.92% of the letters included calibration issues and 11.32% of them were related to maintenance issues.

In most of the cases, the calibration related issues could have been prevented if the companies had a compliant software solution set up.

Research results

Some important info on the research

  • For this research we used data from the FDA warning letters database for the years between 2013-2017.
  • In order to define which warning letters are related to calibration issues, we searched for warning letters that contained the word ‘calibration’. So, we haven’t counted any possible warning letters with calibration related issues that don’t contain the word ‘calibration’.
  • Similarly, to define which warning letters include maintenance issues, we searched for warning letters that included the word ‘maintenance’. It is possible that there are more warning letters relating to maintenance that haven’t been included in the research because they don’t include the word ‘maintenance’ in their content.


3274 warning letters have been issued since 2013. In 2017, FDA issued less warning letters than in any other year between 2013-2017.

Table with total number of FDA warning letters

Calibration Issues

There is a decrease in warning letters that include calibration issues. In 2016 and 2017 only 3.66% and 3.51% of the warning letters included calibration issues, respectively.

Table of FDA warning letters calibration

4.92% of the warning letters between 2013-2017 included the word ‘Calibration’.

Chart of FDA warning letters with calibration issues

Warning Letters by Industry Sector

The warning letters were reviewed and divided in the following industry sectors:
• Life Sciences: pharmaceutical, medical manufacturer, dietary supplements, laboratories etc.
• Food & Beverage: food producers, food powder producers, grocery etc.
• Manufacturing: This category includes companies that produce implants, protective garments, surgical gowns and masks etc.

Life Sciences industry has received the vast majority of the warning letters between 2013 and 2017. To be more precise, 3 out of 4 warning letters have Life sciences companies as recipients.

Pie chart of FDA warning letters by industry

As we see in the following table, the vast majority of Life Sciences warning letters include calibration issues. In some cases, the amount of  Life Sciences warning letters relating to calibration reaches over 80% of the total.

Bar chart for life sciences calibration related warning letters

Countries with the most inspections and number of warning letters relating to calibration.

The top five countries with the most inspections between 2013 and 2017 are: US, India, Germany, Canada and China. China has the smallest number of inspected companies but the highest percentage of companies that received warning letters with calibration issues (10.26%). The country with the second highest percentage of companies with warning letters that include calibration issues is Canada (1.69%).

Bar chart of countries with most inspections

In our following article we are exploring the cost of receiving a warning letter. Stay tuned!

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